Ground lining, covering and method for laying a green area

ABSTRACT

A ground lining for regulating the water balance of an area of ground has a combination of ground panels ( 5 ) which can be placed against each other and a panel covering ( 51 ) which has a number of openings ( 16   a, b ) to allow the passage of water. The ground lining ( 6 ) also comprises a panel base ( 52 ) which is located at a distance from the panel covering ( 51 ), several reservoirs ( 54 ) being provided between the panel base ( 52 ) and the panel covering ( 51 ). These reservoirs are separated from each other by dividing walls ( 53 ) that extend between the panel base ( 52 ) and the panel covering ( 51 ) and adjacent reservoirs ( 54 ) are interconnected by an overflow ( 55 ). According to prior art, moisture is only stored above the level of the panel in direct contact with the surface structure or the surface that is walked on. According to the invention, the reservoirs ( 54 ) that extend under the panel base ( 52 ) ensure a longer-lasting storage capacity and therefore a longer moisture supply phase to the structure above. Another ground lining is composed of a combination of rectangular ground panels ( 5 ) which are laid against each other and are delimited by peripheral side walls ( 56 ). Two side walls ( 56 ) are adjacent through a corner each have a molded-on elastic hook ( 8 ) for connecting adjacent ground panels ( 5 ).

BACKGROUND OF THE INVENTION

The present invention relates to a ground lining, a covering forcreating a green area or a sports field as well as a method for laying agreen area.

Ground linings for regulating the water balance of an area of ground,for example, of a sports field are disclosed in German PatentApplication DE 197 20 006 A1. Described there are grid panels which areinterconnectable to form a lining and which have elevations anddepressions at their upper sides for storing a residual moisture. Theseground linings have proven to be efficient for covering structureshaving a normal moisture requirement. For covering structures having anincreased moisture requirement or green areas which are subject to along dry period, increased demands are made on the regulating capabilityof the water balance in the ground.

A further ground lining as well as a covering for creating a ridingfield is described in German Patent Application DE 44 16 943 A1. Theupwardly open design of the ground panels with the upwardly projectingedges of the individual hexagonal panel elements are, on one hand,sensitive to damage, in particular, when the ground panels are laid bareas part of a riding field covering. This will then also involve a riskof injury to the persons or animals stepping on the covering. Moreover,the water regulating capability of such an open structure is reduced.

The same applies to the grid panels which disclosed in the publicationsU.S. Pat. No. 5,816,738; DE 297 07 770 U1; DE 196 32 070 C2; EP 0 516957 A1 und DE 44 15 595 A1 and which are partly usable for grass areas.

Also, with respect to the ability of ground linings to be laid overlarge surfaces, it is useful for these ground linings to be able to bequickly laid down onto the subgrade or the surface of the ground; here,increased demands are to be made on the connecting elements between thepanels in terms of flexibility and strength.

In the case of ground elements having variations in temperature, it mustbe possible to compensate for expansions between the panels. Theintention for the present invention is, moreover, to contribute toaccelerate the laying of green areas even in difficult ground andclimate conditions by means of a suitable method.

SUMMARY OF THE INVENTION

The present invention provides a ground lining for regulating the waterbalance of an area of ground comprising a combination of ground panels(5) which can be placed against each other and which feature a panelcovering (51) having a plurality of cover openings (16 a, b) to allowthe passage of water, wherein the ground lining (6) features a panelbase (52) which is located at a distance from the panel covering (51),several reservoirs (54) being provided between the panel base (52) andthe panel covering (51) and separated from each other by dividing walls(53) that extend between the panel base (52) and the panel covering(51); and adjacent reservoirs (54) are interconnected by an overflow(55).

The present invention also provides a ground lining comprising acombination of square ground panels (5) which can be placed against eachother and which are bordered by surrounding side walls (56), wherein twoside walls (56) meeting at a corner each have an integrally molded hook(8) for connecting adjacent ground panels (5) and the remaining two sidewalls (56) feature pockets (81) for the engagement of the hooks (8).

A covering of a sports field or of a green area is also provided, thecovering comprising a subgrade (1) and an overlaying surface structure(2) featuring at least one walked-on layer (7), wherein a ground lining(6) is arranged between the walked-on layer (7) and the subgrade (1). Amethod for laying a green area is provided, comprising the followingmethod steps: construction of the covering; the ground lining (6), whichis filled with a substrate which promotes the growth of grass or withliquid, being laid prior to placing the walked-on layer (7); applyingthe walked-on layer (7), sprinkling grass seeds over the walked-on layer(7), and watering the walked-on layer (7).

The regulation of the water balance within the structure of the coveringis essential for the lasting preservation of green areas such a grassarea, sports fields, etc. To minimize the cost intensive artificialirrigation outlay, especially during dry periods or in climaticallyunfavorable regions of the earth, the present invention makes provisionfor reservoirs for storing water to be integrated in the ground panel.While in the related art, provision is made for the moisture to bestored only above the panel plane, in direct contact with the overlayingsurface structure or the layer that is walked on, the reservoirs thatextend underneath the panel base ensure a longer-lasting storagecapacity and therefore a longer moisture supply phase to the structureabove. It is important for this that the reservoirs be configured insidethe ground panel in a closed manner, that is without direct contact tothe overlaying covering structure. The overflows between the reservoirsensure that a locally increased accumulation of water can be distributedover the adjacent reservoirs so that a homogeneous water regulatingcapability is provided in the cover or ground lining. By an additionalprofiling of the panel covering, for example with elevations anddepressions, it is possible, on one hand, to influence the regulatingcapability additionally and, on the other hand, to increase thestiffness of the ground lining, which is advantageous in the case ofcompressive loading of the lining. The adhesion and interconnection withthe adjacent layer is increased as well.

It is to be regarded as a further advantage that, using the surfacecontour of the ground panels constituted by the elevations anddepressions, it was possible to find a surface contour which counteractsthe flow behavior of the walked-on layer and which not only prevents thewalked-on layer from being laterally displaced between the elevationswithin the walked-on layer but which also suppresses a lateraldisplacement above the elevations in an effective manner. This effect isbased on that fact that a local compressive load gives rise to a conicalpressure distribution in the walked-on layer which is largelycompensated for due to the surface of the ground panels which isstructured by elevations. This compensation effect is intensified by thewall of the elevations which is slanted in design and generally has aconical or pyramidal shape so that, in response to the pressure, forexample of a horse's hoof, an oppositely directed pressure distributiondevelops in the walked-on layer. This pressure distribution counteractsthe conical pressure shape resulting from the horse's hoof. Thus, thehorizontal pressure component underneath the horse's hoof is largelyneutralized and a lateral spreading of the walked-on layer (sand) abovethe elevations is effectively prevented. In a further embodiment of thepresent invention, the elevations are staggered by rows so as to hinderthe walked-on layer from flowing along the troughs. Such an arrangementensues also in a chessboard-like arrangement of the elevations when, inlieu of a trough crossing, an elevation is located between four adjacentelevations. These second elevations can then have a different designthan the aforementioned first elevations. The second elevations could bedesigned, for example, without depression or smaller.

Should the ground panels nevertheless be locally cleared of thewalked-on layer, then the surface structure turns out to be largelyinsensitive to impact effects since the elevations are always designedto have a larger surface than a web-like partitioning of the surface.Therefore, damage to the ground panels by an external influence and aresulting risk of injury are not to be expected.

A further advantage of the ground lining consists in the flexible designof the ground panels which ensues from the waved structure of thesuccessive elevations and troughs. Advantageous is also the flexibilityof the panel perpendicularly to the panel plane. A loading of the groundpanel gives rise to a local plunging of the elevations into unfilledhollow spaces underneath the ground panel, enabling the flexibility. Theelasticity of the ground lining resulting from this ensures unvaryingground conditions over a large surface.

The design of the ground lining according to the present invention makesit suitable for coverings of any kind so that the ground lining is alsosuitable for driveways and walkways as well as for storage areas inwarehouses where it is directly contacted.

By forming hooks on the edges of the ground panels on both sides of acorner, it is possible to form a large-surface interconnected groundlining which can also be wound onto and unwound from a mandrel so that arapid laying of large-surface ground linings is possible. The U-shapeddesign of the hooks permits the flexibility required during the windingup and unwinding of the lining, i.e., of the panels.

Because of the capability of filling the reservoirs in the ground panelsalso with substrates which promote ground or green area growth, it ispossible to accelerate the creation of a green area by laying groundpanels which are filled in this manner.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantageous embodiments of the present invention will be explained inthe following with reference to the attached drawing:

FIG. 1 shows a schematic cross-section of a green field covering withground panels;

FIG. 2a is a top view of the ground panel according to FIG. 1;

FIG. 2b shows a cross-section of the ground panel according to FIG. 2a;

FIG. 3 is a top view of a ground lining composed of interconnectedground panels;

FIG. 4a shows a cut-away portion of a ground panel including a hook;

FIG. 4b is a view of two ground panels which are interconnected viahooks; and FIG. 5 is a perspective representation of a ground panel.

DETAILED DESCRIPTION

The covering of a lawn for a golf course as shown in a sectional view inFIG. 1 is composed of a subgrade 1 and an overlaying surface structure2. Subgrade 1 can be a foundation of gravel, grass, loam, sand or humus.If necessary, the subgrade is leveled to eliminate rough unevennesses soas to prepare it for surface structure 2. Subsequently, the individuallayers of surface structure 2 are placed onto the so prepared subgrade1. Surface structure 2 is composed, in an upward direction, of a lowersand layer 4, of a ground lining 6 composed of ground panels 5, and of awalked-on layer 7 composed of grass and humus. Ground panels 5 aremanufactured from thermoplastic material, recycled material being usedas well.

As is further discernible in FIG. 1, ground lining 6 is composed of aplurality of interconnected ground panels 5, the connection of adjacentground panels 5 being effected via several flexible hooks 8. Due to theelastic connection of ground panels 5, it is first of all possible forground lining 6 to conform to unevennesses stemming from the subgradewithout giving rise to gaps between ground panels 5. In this manner, itis also ensured that ground panels 5 cannot be driven apart by anexternal influence.

In terms of the geometric layout of ground panels 5, they areadvantageously configured as a regular polygon, the exemplaryembodiments according to FIGS. 1, 2 a, 2 b, 3 and 5 depicting groundpanels 5 having a square layout.

The side length of 200 or 250 millimeters chosen for the exemplaryembodiments according to FIGS. 2a, b and 5 allows ground lining 6 to beunwound in sheets so as to allow a rapid laying of ground lining 6.

As can be gathered from FIGS. 2a and 2 b, ground panel 5 is constitutedby a panel covering 51 and a panel base 52 which are spaced from eachother by vertically extending dividing walls 53. As shown in brokenlines in FIG. 2a, dividing walls 53 run in the form of a grid, thusdividing the hollow space of the ground panel into reservoirs 54 lyingside-by-side in a chessboard-like manner.

Adjacent reservoirs 54 are interconnected via overflows 55 so that it ispossible for water to enter the reservoirs via cover openings 16 a and16 b provided in panel covering 51, and to distribute uniformly overreservoirs 54.

In case that ground panel 51 is located in an inclined position on aslope, the water can be retained in an uphill direction as well. To thisend, overflows 55 are formed in dividing walls 53 near panel covering51. Overflows 55 are designed as wall apertures.

As is further discernible in FIGS. 2a and 2 b, ground panel 5 isencircled by a surrounding side wall 56 whose edges extend beyond panelcovering 51. The edges terminate level with elevations 9 formed in panelcovering 51.

FIGS. 2a and 2 b depict, moreover, the profiling of panel covering 51.Each ground panel features pyramidally-shaped elevations 9 which areformed on panel covering 51 in a chessboard-like manner, each panelcovering 51 being divided into nine equally sized square fieldsaccording to the arrangement of reservoirs 54, the square fields eachhaving a centrically arranged elevation 9. Troughs 10, which areV-shaped in cross-section, extend between elevations 9. Elevations 9,which are similar to the frustum of a pyramid, terminate in an upwarddirection in an annular edge, the so-called “crater edge” 12. Thecontour of the elevation ensues from the combination of apyramidally-shaped base which merges continuously up to annular crateredge 12 into a conical shape; from there on, crater edge 12 extendsvertically upward. A crater-shaped depression 13, which originates atcrater edge 12, extends centrically into the interior of each elevation9.

To support the regulation of the water balance, crater edges 12 areprovided with cover openings 16 b so that it is possible for water fromtroughs 10 to flow off into subgrade 1 via the cover openings of crateredge 12 as soon as it reaches the crater edge. Cover openings 16 b ofcrater edges 12 are designed as bore holes which extend vertically intothe crater edge and whose diameter is larger than the wall thickness ofthe crater edges so that slot-shaped cover openings 16 b extend from thebase of the edges. Water flowing into depression 13 flows off via coveropenings 16 a which are centrically formed in depression 13.

Panel covering 51, dividing walls 53 as well as side walls 56 aremanufactured separately from panel base 52 using the injection moldingor deep drawing method.

A combination of several ground panels 5 is depicted in FIG. 3. Usingtwo hooks 8 which are in each case formed on two side walls 56 meetingat a corner, adjacent ground panels 5 are connected to form a groundlining 6. In the other two side walls, provision is made in each casefor pockets 81 for the engagement of hooks 8. Hooks 8 are formed on sidewalls 56, which can be carried out integrally in the case ofinjection-molded parts.

Ground panels 5 of adjacent rows are arranged without offset from eachother, that is in a chessboard-like manner so that it is possible for aground lining 6 to be wound up on a mandrel and, consequently, to bequickly unwound for laying. Arched hooks 8 ensure the flexibilitybetween the ground panels which is required for this so that an elasticflexibility of ground panels 5 relative to each other is made possible,in particular in the panel plane, as is discernible in FIGS. 1 and 3.Tensions which can develop in the ground panels due to irregularities ofthe underlying ground can thus be considerably reduced.

FIGS. 4a and 4 b depict hooks 8 for the elastic connection of adjacentground panels 5.

Hooks 8 have a U-shaped or arched section 82; a leg 83, which is formedat a distance from side wall 56, being arranged parallel to side wall56. In the region of hook 8, side wall 56 has a cut-out 84 which hook 8extends into. Leg 83 is joined to adjacent dividing wall 53 in aT-shaped manner, which prevents hook 8 from bulging or even tearing offfrom side wall 56 under load. Provided at the free end of hook 8 is atongue 85 which has a flexible design and which, during the engagementof hook 8 with pocket 81 of adjacent ground panel 5, elastically snapsinto an undercut 84 formed by the pocket. Thus, for inserting hook 8into cut-out 84 of the adjacent ground panel, it is inserted into thecut-out from above essentially perpendicularly to the panel plane.Consequently, the flexibility of this connection runs essentiallyperpendicularly to the direction of engagement of hook 8, which, on onehand, prevents hook 8 from slipping out under stress and, on the otherhand, supports the elastic flexibility in the panel direction.

FIG. 5 shows an alternative embodiment of a ground panel 5 withoutelevations and without panel base. Hooks 8 terminate level with thesurface of the ground panel which is provided with numerous openings forthe passage of water and/or light. Ground panel 5 is suitable for beinglaid as a superficial ground lining, on one hand, for reinforcing theground and, on the other hand, to protect it from damage from beingintensively walked or traveled on. The connection of the ground panelsvia the above described hooks 8, makes it possible for the ground liningto be wound up and unwound.

LIST OF REFERENCE SYMBOLS

1 Subgrade 2 Surface structure 4 Sand layer 5 Ground panel 51 Panelcovering 52 Panel base 53 Dividing wall 54 Reservoir 55 Overflow 56 Sidewall 6 Ground lining 7 Walked-on layer 8 Hook 81 Pocket 82 Section 83Leg 84 Cut-out 85 Tongue 9 Elevation 10 Trough 12 Crater edge 13Depression 16a, b Cover opening

What is claimed is:
 1. A ground panel for regulating water in an area ofground comprising: a panel covering having a plurality of cover openingsto allow the passage of water; and a panel base being located at adistance from the panel covering so as to define a first reservoir andan adjacent reservoir between the panel base and the panel covering, thefirst reservoir being separated from the adjacent reservoir by at leastone dividing wall extending between the panel base and the panelcovering, the first reservoir and the adjacent reservoir beinginterconnected by an overflow, wherein the panel covering includes atleast one of elevations and depressions spaced from each other bytroughs, the elevations defining the depressions, the depressions beingcrater-shaped.
 2. The ground panel as recited in claim 1, wherein thefirst reservoir and the adjacent reservoir are two of a plurality ofreservoirs, the plurality of reservoirs being arranged side-by-side in achessboard-like manner.
 3. The ground panel as recited in claim 2wherein the plurality of reservoirs numbers between four or ninereservoirs.
 4. The ground panel as recited in claim 1 wherein theoverflow is formed by an aperture in the at least one dividing wall. 5.The ground panel as recited in claim 1 further comprising a surroundingside wall surrounding the panel, the side wall having edges extendingbeyond the panel covering.
 6. The ground panel as recited in claim 1wherein at least one of the troughs, the depressions and edges of theelevations include at least one cover opening for accessing the firstreservoir.
 7. The ground panel as recited in claim 1 wherein at leastone of a single elevation and single depression in the panel coveringcovers the first reservoir.
 8. The ground panel as recited in claim 1wherein the elevations each have an annular edge, the edges terminatinglevel with a side wall edge of the panel.
 9. The ground panel as recitedin claim 1 wherein annular edges of the elevations have cover openingsformed by bore holes whose diameter is larger than a wall thickness ofthe edge.
 10. The ground panel as recited in claim 1 wherein the panelcovering, the at least one dividing wall and a side wall bordering theground panel are formed from an injection-molded or deep-drawn partseparate from the panel base.
 11. The ground panel as recited in claim 1wherein the panel base is filled with a fertilizer.
 12. A ground liningcomprising a plurality of combined ground panels as recited in claim 1.13. The ground lining as recited in claim 12 wherein the ground panelsare rectangular and further include surrounding side walls, two sidewalls of a first ground panel meeting at a corner, with each of the twoside walls having an integrally molded hook for connecting adjacentground panels, the first ground panel having two remaining side wallsincluding pockets for the engagement of hooks of other ground panels.14. The ground lining as recited in claim 13 wherein the hook has aU-shaped section, a leg arranged parallel to one of the side walls, theleg being transversely joined to the side wall at a lateral distancetherefrom.
 15. The ground lining as recited in claim 14 wherein in theregion of the hook, the respective side wall has a cut-out into whichthe hook extends, a leg being joined to a web which projects verticallyfrom the panel covering.
 16. The ground lining as recited in claim 12wherein the hook has a tongue at its free end, the tongue having aflexible design and elastically snappable into an undercut during theengagement of the hook with a pocket.
 17. A covering of a sports fieldor of a green area comprising: a subgrade; an overlaying surfacestructure having at least one walked-on layer; and a ground lining asrecited in claim 12 arranged between the walked-on layer and thesubgrade.
 18. A method for laying a green area, comprising the steps of:constructing the covering as recited in claim 17, the covering includinga fertilizer; applying the walked-on layer after laying the covering;sprinkling grass seeds over the walked-on layer; and watering thewalked-on layer.